Means and method of making electrode strands



Dec. 30, 1947. 1.. c. WERNER 2,433,497

' MEANS AND METHOD OF MAKING ELECTRODE STRANDS Original Filed Sept. I27, 1941 INVENTOR A C. [FA 5E.

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ATTORNEY Patented Dec. 30, 1947 'D STATE-S Original; application-September 27, 1941, Serial No. 412,546, now Patent No 2,398,609,;datedApril 16, I946. Divided and' tliis application July 14, 1943, Serial'No.494,621

6 Claims. (01. f llF l l This'invention relates in general to meansandmethod of making electrode strands, and is a division of thesubject-matter of application; Serial No; 412,546, filed September 27,1941 and now issued as Patent Number 2,398,609, April 16, 1946.

Some attempts have heretofore been made to construct and use electrodesof a dome-like or bird-cage formation. Difii'culties have arisen bothinthe manufacture of the strands forming such an electrode and in theassembly and re"- tention of those strands in the electrode structure:In such patents as 2,238,596 of April 15 194-1, in the name of I. E.Mouromtseif et ali, as signed to the same assignee as the present"applieation', a bird-cage structure of cathode is i1- lustr'atedwherein-the strands forming the same arese'cured at their upper ends ina contiguous grouped arrangement by means of a length of wire-coiledaround the ends of said strands bind-- ing' them together. It has beenfound that in ternal stresses are created in such an' assembly whicheither immediately or after a short period of time result inthe strandsof the electrode be= coming displaced from their original position,getting out of parallel and affecting the tube characteristics;

Kttempts have been made in connectionwitli such'electrodes; as shown insaid patent, to weld a'slipcoil; comprising a spirally wound bindingwire; onto the contiguous parts of the" strands; While the welding of aslip coil has obtained" a better electrical contact, the weld cannotbe'co'nfine'd sufilciently, but burns down the side of the slip'coil tothe bottom of the spiral winding, setting' up stresses in the strands ofthe electrode which result in as bad or worse displacement anddeformation as that explained above; This defect has been overcome tosome extent in grids bys'pot welding hoops at intervals of height of thegrid. It must also be noted in the patent referred to that the structuredisclosed isa cathode and not a grid. This fact is pointed out in that afeature of the present invention is the construction of a grid of acharacter enabling the grid-to form part of an electrical circuit and beheated by current travellin through the grid wires during themanufacture of the electronic device. It is accordingly not possible tohold the strands-with hoops either in a cathode or in my improved grid.The heating of the grid is'per formed atthe same time that the cathodeis similarly-heated, andconsequently the electronic de vice 'may-beexhausted in minimum-time by vi'r-'- 2. t-ueof the greater amount ofheat developed by lighting both elecfil'fid'sat th' salni'e timeiAccordingly, an object of the present invention is" toprovideanimprove'dmethod of manufacturing electrode strands;

Morespecifically, an object of the invention is to rapidly andaccurately" form a plurality of str'an'dsdh a roup;-

Alibther'objeot o'f the lfivehfidrf is t'O' form eleh trdde strand sfiom parts of convolutions of wire:

A further object-of the invention isto provide slack in the convllitlbhsOf W-i fea'fld. utillz e'the slack by forcing the wire into depressions.

lFet another-obj'e'ct? of the invention istopro vine improved means -forforming the wire in desi'retl' configuration of strands.-

Still-further objects-of the invention will ap pear as" the" descriptionproceeds; both" by direct recitation thereof andby implication from thecontext- Refeflllig to the accompanying drawing; in which likenumeralsof' reference indicate similar partsthroughout theseveralviews:-

F'igure 1 isa central vertical se'ction' of an elect-"rb'iiic' dischargedevice'and showing my invention applied thereto;

F fire 3 -is a-verticalsectionalview of the'peak efidof tliedbine -likebird cage' grid formation of Fig; 1;

Figuresisan elevationof- One of the grid strands;

FigureGis-a vertical sectional view of a means for forming strands fromconvolutions of wire; taken in tlie' plane of'a convolution of the wire;

Figure'7 "i"sview similar to Figure 6 and show ing the slack in theconvolutio'nsof wireforced' into areasof depression in the mandrel forshapingthe'wire prior to-cutting the formed strands therefrom; and

Figure 8 isan edge view' of'the forming means with-the convolutions orwire thereon.-

Referring to-s'aid"drawings, a part of an electronicd'ev'i ce; generallyidentified as a power tube,

isillustrated showing niyinvention as part there ofiIt"shouldbeunderstoodj however, at the out-- set that my: invention isapplicable to other elec-' tronic devices than this particular powertube. The specific time shown comprises a glass or othercer'amiccasin'g'portion' l0, here shown as parto'f the evacuatedenvelope, andasalsojco nstitutirigtliebase portion for the device and hav portion 3to a dome-like anode M of suitable metallic material adapted to thepurpose. A part of the anode proper is shown re-entrant with respect tothe connecting ring portion l3, thereby providing an annular upwardlyopen groove l5 within which is situated a member Hi hollowed out tosubstantially fit the dome-like.

Within the dome-like cavity formed by anode l4, and preferably having acontour or formation likewise of the same dome-like characterparalleling the inner dome-like surface of the anode, so as to be evenlyspaced therefrom, is a birdcage dome-like grid l8 constituting anessential feature of the present invention.

The said grid comprises a plurality of similar strands evenlydistributed circumferentially and providing lower portions l9 which areupright and parallel to each other. Toward the top of the strands thesame curve upwardly inwardly, as at 23, converging toward each othertoward a common central point on the central axis of the grid. Slightlyaway from such central axis, the strands are bent upward forming uprightneck portions 2| which are likewise parallel to each other and arearranged successively contiguous to each other and contiguous to acylindrical core 22 axially disposed with respect to the grid and of alength substantially equal to the length of said neck portions 2| of thestrands. On the outside of the strands is situated a gripping collar 23likewise of substantially the length of the neck portions 2| of thestrands. The collar 23 and concentrically situated core 22 provide justample room therebetween for the neck portions 2| of the strand and gripsaid neck portions in the assembly as clearly shown in Figures 3 and 4.Preferably, after the neck portions 2| of said strands, core 22 andcollar 23 are assembled, the same are unified by welding at the outerends of the neck portions 2| of said strands. The presence of the core22 and collar 23 will prevent the arc performing the weld fromtravelling down to the curved portion 26 of the strands, and as a matterof fact, the arc and weld will be confined to the extreme end of thecore and collar well away from the lower ends of said core and collarand from the part of the strands where emerging therefrom or whereprotruding therebelow. Accordingly, while the welding secures thedesired unification between the parts mentioned, yet internal stressescreated within the strands will be confined to the extreme upper ends ofthe neck portions thereof and by virtue of the gripping action at thelower ends of the core and collar and the contiguous situation of theneck portions of the strands between the core and collar,- no deflectionor distortion will result in the exposed parts of the strands. By virtueof the construction thus described, the exposed portions of the strandswill remain in their given positions and accordingly will remain evenlydistributed with the lower parallel portions remaining parallel andequal distances apart at all times. 7

At the lower part of the grid, transverse thereto, are situated two flatannular members which may be conveniently referred to as rings 24, 25.These rings are separated physically and electrically by interveninginsulators 26 and are held in such position by suitable screws, or thelike, 27 extending through said insulators and insulated from the plateunder the head of said screws, as by insulating washers 28. The innerperiphery of the upper ring 24 is provided with a series of evenlyspaced cutouts 29 corresponding to the spacing of alternate gridstrands, thereby enabling such alternate grid strands to pass throughthe cutouts 29 without engaging the upper ring whereby the lower ends ofthose alternate strands may be introduced into and secured 'within holes30 arranged in a circular series near the inner periphery of the lowerring 25. The intermediate strands of the grid are introduced into holes3| in the area of the ring intervening between the said cutouts, saidholes likewise being in a circular series the radius of curvature of theseries for both rings preferably being identical whereby all of thestrands will have equal spacing from the axis of the grid where attachedto their respective rings. At different parts of the peripheries oi thesaid rings, the same are formed with outward extensions 32, 33,respectively, forming means i or attachment of the appropriateconducting posts I2.

During the manufacture of the electron discharge device, current isapplied by way of one post |2 to one of the rings, for instance ring 25,passes upwardly of the grid through the alternate strands 30 to the peakwhere those strands make electrical contact with the intermediatestrands and is conducted thereby downwardly to ring 24 and thence backto the current source by way of the post 12 connected with that ring.This heating is effected at the same time that heat is applied to thefilament and is a material factor in reducing the exhaust time for thedevice to a minimum. Tubulation 34 is provided in the base portion H] ofthe envelope as a means for evacuation, said tubulation being sealedafter the ex-- haust process is completed.

The filamentary cathode, now identified by reference numeral 35, has asimilar construction to that just given in description of the grid. Thatis to say, said filament is supported by two conductive rings 35, 31which are parallel but insulated one from the other and connected withalternate and intermediate strands of the filament, further descriptionwhereof is deemed unnecessary, except to say that the neck portions ofthe strands forming said cathode are bent downwardly instead of upwardlyand are appropriately secured to a core and gripped by a collar ifdesired just as described above. It will now be recognized that thefilament is of dome shape with the general contour of its upper endsemi-spherical and that the grid has its general contour at the insidetoward the filament likewise semi-spherical. This enables the grid andfilament to be closely spaced and to have substantial parallelismthroughout the portion of the grid which is opposed by the filament.

In connection with my improved electron discharge device, wherein arerequired grid strands of the special shape shown in Figure 5, I havealso provided a means and method of making the same. I provide a mandrel38 having straight sides 39 to conform the wire with a straight portionto provide portion l9 thereof heretofore described. The upper end of themandrel provides rounded shoulders 45] to conform the wire to form thecurved or arcuate portion 20 of the strand. At the middle and top of themandrel is provided a cross rib 4| standing upright so as to present anouter uprightsurface to conform the wire to form the upright neckportion 2| of the strand. Said rib is of greater height than theultimately desired height of the neck portion 2] ofthe strand, asaw-slit 62 being provided on opposite sides of the rib a distance abovethe shoulder 40 equaltethe desired height of neck 2| to be produced;Toward the bottom of the mandrel are providedsidesaw-slits 43, 43, at adistance below shoulder 30 equal to the desired length of the straightportion- |9- of the strand; Below these side saw-slits the mandrel ispreferably semicylindrical in order-tofacilitatewinding the wiretherearound;

At the endsofthe mandrel are end plates 44 which arelarger than thecross-sectional area of the mandrel soas to forma flange around the sameto prevent the Wound wire from slipping off the ends of the mandrel.Said end plates 44 are also conveniently utilized to mountslackproducing cross bars 65. These bars may be temporarily held inplace by screws 46 passing therethrough and entering the edges of thesaid end plates. It is preferable that the cross bars be applied wherethey will introduce the least bending of the wire when Wound around themandrel, and I have accordingly shown them applied in Figure 6 aboutmidway of the height of the flat sides of the mandrel. In the process ofmanufacture the wire from which the strands are made, is wound incontinuous convolutions 41 around the mandrel while the cross-bars arein position. Accordingly, each convolution is given a predeterminedamount of slack where it is caused to diverge from the mandrel to passover the said cross-bars. The amount of slack is arranged to equal thelength required to subseguently force the convolutions into the cavityor depression formed by the rounded shoulder and rib of the mandrel. Inthe process of manufacture, after the convolutions have been completed,the cross-bars 45 are detached and removed, thus making the slackavailable in the several convolutions. The next step is to propel a died8 downwardly over the rib 4!, said die having a bottom slot 49 ofappropriate size and shape to receive the rib and accommodate thethickness of Wire situated on the rib, pressing the wire inwardlyagainst the rib as said die descends. The parts are proportioned so thedie will cause the wire to snugly engage both side faces of the rib andboth shoulders, and will take up the slack in the wire and cause thewire to also snugly engage the straight side portions 39 of the mandrel.The die is retained in place, as by pins 5!], and the assembled mandrel,die and formed wire thereon are heat treated as usual in preparation ofgrid wires. The heat treatment obtains a permanent set of theconfiguration given to the wire on the mandrel, and after removal fromthe oven or other place of heat treatment, the die 48 can be removed andthe convolutions will remain snugly engaging the mandrel in view oftheir rigidity developed by the treatment. A cutter 5| is now applied tothe convolutions at the proper places to sever the same at the upper endof neck '2! and at the lower end of straight portion l9. As previouslyindicated saw-slits 42 and 43 are provided in the neck and mandrel, andthose slits also extend into the end plates 44 thereby enabling thecutter 5| to perform its function upon the convolutions at theprescribed places.

It will accordingly be seen that I have provided a convenient method forthe manufacture of the specially formed. strands of my' improved?electrodes and that. the electrode is one: wherein the foregoing.objects: are. accomplished both in the electrode per. se and in thecombination thereof with the; other electrodes.

I. claim:.

1-. A method: of. manufacture of. electrode strands, comprising, windingwirein convolutions around a mandrel having" a depression, forcing thewire into; the depression after windingv of the convolutions iscompleted, and' holding, the wire depressed, heat-treating the wirewhile held depressed. for forming the wire and cause it to retain-theshape given while held depressed, and sever-ingthe wire at parts'of theconvolutions on opposite sides of the depression after it is formed inthe shape; desired. by the heat. treat:- ment,

2. A method of manufacture of electrode strands, comprising winding wirein convolutions on a mandrel having areas substantially conforming tothe desired strand shape and including formative areas of depressioninto which the strands are'to be bent, increasing the circumferentiallength of convolutions to accord with the length needed to depress intosaid depressions, partially releasing the wound wire to create slack tothe extent of the said increase of circumferential length ofconvolutions, and taking up said slack and forming the convolutions inthe formative areas of depression of the mandrel.

3. A method of manufacture of electrode strands comprising winding wirein convolutions on a mandrel having areas substantially conforming tothe desired strand shape and including formative areas of depressioninto which the strands are to be bent, increasing the circumferentiallength of convolutions .to accord with the length needed to depress intosaid depressions, partially releasing the Wound wire to create slack tothe extent of the said increase of circumferential length ofconvolutions, taking up said slack and forming the convolutions in theformative areas of depression of the mandrel, heat-treating theconvolutions thereby securing permanent set in the formed shape, andcutting the convolutions at a plurality of places in each convolution.

4. Means for manufacture of electrodes, comprising a mandrel having endflanges and a reduced transverse neck between said flanges providing aformative area of depression for wire wound around the mandrel, meanslengthwise of the mandrel over which the wire is wound to space the wirethereat from the mandrel, said means being removable and therebyaffording slack in the convolutions of wire around the mandrel, andmeans for pressing the wire into the formative area and for therebytaking up said slack therein.

5. Means for manufacture of electrodes, comprising a mandrel having endflanges and a reduced transverse neck between said flanges providing aformative area of depression for wire wound around the mandrel and meanslengthwise of the mandrel over which the wire is wound to space the wirethereat from the mandrel, said means being removable and therebyaffording slack in the convolutions of wire around the mandrel, a diedepressable onto said neck for pressing the wire into the formative areaand for thereby taking up said slack therein, and mean for retainingsaid die in place whereby the convolutions are retained temporarily informed condition thereby until set to form.

6. Means for manufacture of electrodes, comprising a mandrel having endflanges and'a re duced transverse neck between said flanges providing aformative area of depression for wire wound around the mandrel, meanslengthwise of the mandrel over which the wire is wound to space the wirethereat from the mandrel, said means being removable and therebyafiording slack in the convolutions of wire around the mandrel, andmeans for pressing the wire into the formative area and for therebytaking up said slack therein, said flanges and mandrel having slitstherein for admitting'a cutter to pass transversely through theconvolutions and sever the same into formed strands.

LEO C. WERNER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

